Just thought i'd let everyone know my battery back worked last night at the show I taped.
Here's how I made it.
4 aa battery holder with lead wires
4 aa rechargeable NiMh's 1800mAh each
Female end of adaptaplug cable
Adaptaplug Size B
Crimp connectors
I just crimped the wires from the battery holder to the adaptacable, then put the adaptaplug on (check polarity), charged the batteries full. Ran them in a flashlight (thanks dklein) for a minute or so, then plugged the jb3 in...
One thing to be careful with that was happening. Whe i first ran the batteries, i didn't kill them enough so the jb3 wouldn't power up. And even with the internal battery in only it wouldn't power up, the machine sort of locked itself off. So i had to remove the internal battery and put it back in, then it started up fine...
I only ran it for the first set 1.5 hours, then switched to internal.. but i'm sure it would have gone a lto longer, i'm gonna do some tests and hopefully post results. But at least i know i can get 4 hours with the single internal and external pack